ONE-DIMENSIONAL GEOMECHANICAL MODELLING AND ITS IMPLICATION FOR FAULT STABILITY IN VX FIELD, BINTUNI BASIN

• Main Author: Andhita, Mellisa
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/75536
• Institution: Institut Teknologi Bandung

VX Field is a giant gas field located in Bintuni Basin, West Papua. In Roabiba sandstone of VX Field, a Jurassic-aged reservoir, Carbon Capture, Utilization, and Storage (CCUS) in the form of Enhanced Gas Recovery (EGR) will be carried out. Fluid injection will affect the faults in this field, either as the trap or as the migration pathway of hydrocarbon. Fault stability analysis in this field can be used to understand the tendency of the fault to be reactivated due to injection and increase of pore pressure. This analysis is done by carrying out a one-dimensional geomechanical approach, where several data are processed to understand the insitu stressregime as well asthe mechanicalrock properties in this field. Data being used in this analysis are wireline log data, including image log, gamma-ray, slowness, and density log, pressure data from field report, fault polygon, as well as depth structure map of the field. The obtained values are vertical stress (Sv), pore pressure (Pp), minimum horizontal stress (Shmin), and maximum horizontal stress (SHmax). Vertical stress value is obtained from density log processing, with the gradient obtained is 0,0245 MPa/m. Pore pressure value is obtained from pressure data as well as empirical equation on density log, with the gradient obtained is 0,012 MPa/m. Minimum horizontal stress value is obtained from leak-off test data as well as empirical equation, with the gradient obtained is 0,0162 MPa/m. Maximum horizontal stress value is obtained from four empirical methods. Results from each method show similar pattern in each well with the average gradient of 0,0282 MPa/m. One-dimensional geomechanical model is used to perform fault stability analysis, including slip tendency (Ts), dilation tendency (Td), and fracture stability (Fs). The results from one-dimensional geomechanical model shows that the regime that predominantly affects VX Field is strike-slip fault regime, and the orientation of maximum horizontal stress is N20°E. Fault stability analysis shows that faults in VX Field are more likely to dilate than to slip. The pore pressure that can be added for the faults in VX Field to reactivate ranges from 3,2 - 142 MPa with mean of 50,3 MPa.